Acetone shouldn't hurt glazed porcelain, but it can play havoc with paint and plastics. Some faucets (in fact most) have some plastic parts that look like metal on and in them. Acetone could very well eat them up. Spilling a bunch down the drain could mess up some plastic parts, including the pop-up assembly. Acetone will soften and disolve some plastics, and can weld them together after it evaporates.